#pragma once

class Singleton final // 不允许派生
{
public:
	static Singleton& instance();

	void SayHello();
private: 
	// 禁用外部创建或销毁
	Singleton();
	~Singleton();

	// 禁用对象赋值
	Singleton(const Singleton&) = delete;
	Singleton& operator=(const Singleton&) = delete;
};
